<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var apple1 = '红苹果';
        var apple2 = '青苹果';
        var temp = apple1;
        apple1 = apple2;
        apple2 = temp;
        console.log(apple1);
        console.log(apple2);
        console.log(alert('hello'))
    </script>
</body>
</html>